In Paris, it’s hard to imagine a day without smart cards. Invented in France in 1979, the small plastic cards get their brains from a computer chip that can be programmed to allow consumers to chat on their cell phones, buy baguettes and ride the metro. Equipped with a password, they can be used as security devices at office complexes and military bases.

While smart cards have been slow to catch on in North America, Europe built its banking networks using the technology instead of the cheaper magnetic strip cards U.S. banks favor. To convert U.S. banks to smart cards would cost more than $12 billion, according to analysts at Frost & Sullivan. But as security concerns mount, U.S. banks will likely make the switch, says Can Elbi, an Amsterdam-based IT hardware analyst for Credit Suisse First Boston.

The following is a look at how smart cards pervade a Parisian’s life, using a fictional character named Isabelle who works as a computer programmer in the modern suburb known as La Defense and lives with her husband, 3-year-old daughter and seven smart card applications.

7 a.m. Isabelle wakes up to the ringing of her cell phone, which like all GSM (global system for mobile communication) phones contains a smart card chip. It’s her boss asking her to report to work early. This version of the smart card, known as a Subscriber Identity Module, or SIM card, can be moved into a new phone, allowing the user to keep stored information such as directories and voice dialing commands.

7:25 a.m. On her way out the door, Isabelle asks her husband to take their daughter to preschool. Once outside, Isabelle steps into a local boulangerie and pays for a croissant with her Carte Moneo, a so-called stored value card. Moneo lets consumers store up to 100 euros (US$110) on the card. Isabelle has Moneo installed on her regular bank card and regularly "charges up" the card at an ATM.

7:40 a.m. Isabelle sails through the metro turnstile with a swipe of her Navigo smart card. (A sensor on the turnstile can read the Navigo pass from a distance of several centimeters).

8:15 a.m. Our heroine arrives at work at La Defense. She waves a smart card near the door’s security reader to gain access to her office building.

8:30 a.m. Isabelle arrives at her meeting. Her boss says she must visit a client near L’Opera to help with an unexpected software glitch.